In an LTE-A (long-term evolution advanced) system, the number of available carrier frequencies becomes more and more, and it becomes more and more important to design a method of low complexity and high efficiency for searching carrier frequencies to satisfy the LTE-A system.
A conventional algorithm for searching carrier frequencies is carried out by primary synchronization signal (PSS) of LTE (long-term evolution) system. On the whole available band, PSS search is performed with a carrier frequency interval of 100 kHZ, so as to calculate a corresponding frequency peak to average ratio, thereby selecting one or more frequencies as candidates for subsequent cell search. The detailed flow is shown in FIG. 1.
However, in the implementation of the present invention, the inventors found that in an LTE-A system, the number of the available carrier frequencies is very large. For example, for BAND1 (2110 MHz-2170 MHz), in a conventional method for searching carrier frequencies, search is performed with a carrier frequency interval of 100 kHZ, and 600 carrier frequencies need to be searched, which takes a very long time. On the other hand, PSS is very sensitive to carrier frequency offset (CFO), and when the CFO is in a range of 400 kHZ, the peak value related to the PSS association is still large, and the obtained C_ratio is very large, which has direct effect on the performance and correct detection rate of the carrier frequencies search. FIG. 2 is a schematic diagram showing a C_ratio between CFO and PSS association taking two PSSs as an example. Furthermore, due to channel fading, the channel condition for different carrier frequencies are different, it is very possible that the search in correct carrier frequencies is influenced by the channel fading, and its C_ratio is lower than that of other carrier frequencies, resulting in failure of the detection.
It should be noted that the above introduction to the background art is given for the clear and complete description of the technical solution of the present invention and for the understanding by those skilled in the art. The above technical solutions should not be deemed as being known to those skilled in the art for having been described in the background art of the present invention.